1. Field of the Invention
The present invention relates to a light-resistant additive and an ink composition containing the same, and more particularly, to a light-resistant additive further having wettability and the ability to stabilize a colorant and an ink composition containing the light-resistant additive.
2. Description of the Related Art
In general, colored ink-jet ink compositions are composed of a colorant, such as a dye or a pigment, a stabilizer and a dispersant, which are used to improve the stability and dispersibiility of the colorant, an organic solvent, and a wetting agent.
Images printed using such an ink composition are exposed to visible light and ultraviolet (UV) light in the air. When these images are exposed to UV light for an extended period of time, since UV light has a higher energy level than visible light, various blemishes develop. For example, the whiteness of printing media deteriorates and changes to yellow. In addition, color images printed using an ink composition having poor light resistance are liable to bleach or discolor. To solve these problems, there is a need to add to ink compositions a light-resistant additive that blocks or absorbs UV light.
The use of a large molecular weight silicon compound as such a light-resistant additive is disclosed in U.S. Pat. No. 6,346,595. However, this silicon compound is not miscible with other components of an ink composition and, due to the large molecular weight, greatly affects the physical properties, for example, the viscosity, of the composition even when the amount of the silicon compound is slightly changed. Accordingly, it is difficult to adjust the amount of the additive used. In addition, although the polymer includes hydrophilic groups in its molecular structure, the hydrophilic fraction with respect to the total amount of the composition is too small to dissolve the compound sufficiently in water, and more time is required to dissolve the additive. Furthermore, the UV absorbing additive reacts with a colorant or other additives in the composition when stored for a long time, leads to phase separation, and deteriorates long-term storage stability.